Co-existence of a cellular network system and a wireless local area network (WLAN) system is always a hot topic and is widely discussed in conferences on 3GPP and IEEE standards. FIG. 1 is a schematic diagram of interference between a cellular network system and a WLAN system in the prior art. As shown in FIG. 1, a wireless station (STA) and a user equipment (UE) simultaneously send data and/or a signalling to an access point (AP) and a base station (BS), respectively. The STA and the UE are geographically close, and an authorized frequency band used by the BS and the UE in the cellular network system is adjacent to an unauthorized frequency band used by the AP and the STA in the WLAN system. For example, both a long term evolution (LTE) cellular network system and a WLAN system may be deployed on adjacent frequency bands near a 2.4 GHz frequency band. As for another example, the cellular network system will contend frequency bands over 6 GHz with the WLAN system in future. As shown in FIG. 1, the cellular network system employs an authorized frequency band ranging from 10 GHz to 11 GHz, while the WLAN system employs an unauthorized frequency band ranging from 9 GHz to 10 GHz. Therefore, the STA and the UE influence each other so that neighbor cell interference will be caused. For example, an uplink from the STA to the AP may interfere with an uplink from the UE to the BS, a downlink from the AP to the STA may interfere with a downlink from the BS to the UE, the uplink from the UE to the BS may also interfere with the uplink from the STA to the AP and the like, and the downlink from the BS to the UE may also interfere with the downlink from the AP to the STA.
To sum up, the above-mentioned interference is caused by that frequency bands of the two wireless communication systems are adjacent. Therefore, the above-mentioned interference is neighbor cell interference or neighbor frequency interference (Neighbor-Cell Interference, NCI).
Therefore, no matter at present or in the future, if frequency bands of the cellular network system and the WLAN system are adjacent, a problem of neighbor cell interference may always exist. Similarly, the problem of neighbor cell interference among two or more wireless communication systems in a same type and among two or more wireless communication systems in different types may also exist if frequency bands of which are adjacent. In addition, as shown in FIG. 1, although FIG. 1 merely shows a scenario that two wireless communication systems are non-co-located, in fact, two or more wireless communication systems may also be probably in a same location and co-located, for example, the BS may be co-located with the AP.